LTC3734 LINER [Linear Technology], LTC3734 Datasheet
LTC3734
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LTC3734 Summary of contents
Page 1
... OPTI-LOOP response to be optimized for a wide range of output capaci- tance and ESR values. The LTC3734 is available in a small 5mm × 5mm QFN package. For 2-phase applications refer to the LTC3735. , LTC and LT are registered trademarks of Linear Technology Corporation. OPTI-LOOP is a registered trademark of Linear Technology Corporation. ...
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... V OA OAOUT STP_CPUB SGND + SENSE – SENSE RDPRSLP ORDER PART NUMBER LTC3734EUH Consult LTC Marketing for parts specified with wider operating temperature ranges. The ● denotes the specifications which apply over the full operating = 25° 5V PVCC SVCC RUN/SS CONDITIONS I Voltage = 0.5V ...
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... FREQSET V = 1.2V FREQSET FREQSET ≥ 2.4V V FREQSET I = 2mA PGOOD PGOOD V with Respect to Set Output Voltage FB V Ramping Negative FB V Ramping Positive FB LTC3734 = 5V unless otherwise noted. MIN TYP MAX UNITS 100 3.2 3.7 4.2 –2.3 –1.5 – 0.8 1.0 1.5 1.9 3.9 3.2 –5 –1.5 1.5 5 – 85 – ...
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... I OUT = 1mA I OUT = 1mA OUT = 1mA Note 4: The LTC3734 is tested in a feedback loop that servos V specified voltage and measures the resultant V Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See Applications Information. Note 6: Rise and fall times are measured using 10% and 90% levels. Delay times are measured using 50% levels ...
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... COMMON MODE VOLTAGE (V) 100 PSIB V = 15V IN FIGURE 1 –50 –100 3734 G10 LTC3734 Maximum Current Sense Threshold vs Percent of Nominal Output Voltage (Foldback 100 PERCENT OF NOMINAL OUTPUT VOLTAGE (%) 3734 G05 Current Sense Threshold vs I ...
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... LTC3734 W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs Temperature –50 – 100 125 TEMPERATURE (°C) 3734 G13 Current Sense Pin Input Current vs Temperature – 1.6V OUT –11 –10 –9 –8 –7 50 125 –50 – ...
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... MOSFETs. Voltage swing at this pin is from ground (Pin 22): Power Supply Pin. The on chip gate drivers This resistor in are powered from this voltage source. Decouple to PGND OA with a minimum of 4.7μF X5R/X7R ceramic capacitor placed directly adjacent to the IC. LTC3734 + . This resistor sets the output voltage 3734f 7 ...
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... LTC3734 CTIO S SW (Pin 23): Switch Node Connection to Inductor. Volt- age swing at this pin is from a Schottky diode (external) voltage drop below ground (Pin 24): High Current Gate Drive for Top N-Channel MOSFETs. This is the output of a floating driver with a ...
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... FB SLOPE 54k 54k COMP OV 1.5μA SHDN RUN RST SOFT- 6V 5.33(V ) START FB RUN 6-BIT VID DECODER VID0 VID1 VID2 VID3 VID4 VID5 LTC3734 R5 DPRSLPVR RBOOT MD DELAY BOOST TOP D1 SW SWITCH PV CC LOGIC BG BOT PGND SENSE PV CC ...
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... SS internal I voltage is gradually released allowing normal, TH full-current operation. Frequency Programming The switching frequency of the LTC3734 is determined by the DC voltage at the FREQSET pin voltage ranging from 0V to 2.4V moves the internal oscillator frequency from 210kHz to 550kHz. 10 Low Current Operation (PSIB) The PSIB pin selects between two modes of operation. ...
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... This current shortens the soft-start period but also prevents net discharge of the RUN/SS capacitor during a severe overcurrent and/or short-circuit condition. Fold- back current limiting is activated when the output voltage falls below 70% of its nominal level whether or not the short-circuit latchoff circuit is enabled. LTC3734 3734f 11 ...
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... The current comparator CC threshold sets the peak inductor current, yielding a maxi- mum average output current I equal to the peak value MAX less half the peak-to-peak ripple current, ΔI Allowing a margin for variations in the LTC3734 and external component values yields (40mV/I ) SENSE MAX ...
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... G switching frequency as described previously. Please no- tice that the above gate driving losses are usually not dissipated by the MOSFETs. Instead they are mainly dissipated on the internal drivers of the LTC3734, if there voltage. CC are no resistors connected between the drive pins (TG, BG) and the gates of the MOSFETs. ...
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... MOSFET is effectively negligible because the cur- rent conduction of the antiparalleling diode. This effect is often referred as zero-voltage-transition (ZVT). Similarly when the LTC3734 converter works under fully synchro- nous mode at light load, the reverse inductor current can also go through the body diode of the top MOSFET and make the turn-on loss to be negligible ...
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... Do NOT apply greater than 7V to the PV The SV CC circuitry of the LTC3734. This supply current is much lower than that of the current for the external MOSFET gate drive. Ceramic capacitors are very good for high frequency filtering and a 0.1μF ~ 1μF ceramic capacitor ...
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... pulling the RUN/SS pin below 1V the LTC3734 is put into low current shutdown (I can be driven directly from logic as shown in Figure 3. Diode D1 in Figure 3 reduces the start delay but allows C to ramp up slowly providing the soft-start function. SS The RUN/SS pin has an internal 6V zener clamp (see Functional Diagram) ...
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... RUN/SS pin voltage reaches its arming voltage, which is INTERNAL PG (OUTPUT OF INTERNAL POWER GOOD COMPARATOR) ) MASKING LTC3734 DPRSLPVR . When V OUT is within the regulation OUT VID BITS V OUT PGOOD 110μs 110μs PGOOD TIME Figure 5. PGOOD Timing Diagram can be ...
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... SS reaches 4.2V LTC3734 1.196V 1.180V 1.164V 1.148V 1.132V 1.116V 1.100V 1.084V 1.068V 1.052V 1.036V 1.020V 1.004V 0.988V 0.972V 0.956V 0.940V 0.924V 0.908V 0.892V 0.876V 0.860V 0.844V ...
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... Minimum On-Time Considerations Minimum on-time the smallest time duration ON(MIN) that the LTC3734 is capable of turning on the top MOSFET determined by internal timing delays and the gate the charge required to turn on the top MOSFET. Low duty cycle ...
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... LTC3734 U U APPLICATIO S I FOR ATIO where AVP is the slope the current sense resistor SENSE m is the number of phases for LTC3734 R3 and R are defined in Figure 6 AVP g is the transconductance gain for the error amplifier about 4.5mmho for LTC3734. V ...
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... The output voltage settling behavior is related to the stability of the closed-loop system and will demonstrate shifts by an OUT the actual overall supply performance. LTC3734 . ΔI also begins to charge or OUT LOAD generating the feedback error signal that OUT to its steady-state value ...
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... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. Although the LTC3734 has a maximum input voltage of 32V, most applications will be limited to 30V by the MOSFET BV . ...
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... The output capacitor ripple current is calculated. The output ripple will be highest at the maximum input voltage: Δ I OUT MAX Assuming the ESR of output capacitor(s) is 5mΩ, the output ripple voltage is: ⎞ V ⎟ Δ ⎠ V OUT LTC3734 1 – 200 ns 350 kHz 2 • • 1 350 kHz ( ...
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... PC trace spacing? The filter capacitors between + – SENSE and SENSE pin pairs should be as close as possible to the LTC3734. Ensure accurate current sensing with Kelvin connections at the current sense resistor. See Figure 8. TRACE TO INDUCTOR Does the (+) plate of C topside MOSFETs as closely as possible? This capacitor provides the AC current to the MOSFETs ...
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... U TYPICAL APPLICATIO Figure 9 shows a typical application using the LTC3734 to power the mobile CPU core. The input can vary from 5V to 24V; the output voltage can be programmed from 0.7V to 1.708V with a maximum current of 20A. By only modifying the external MOSFET and inductor selection, higher load current capability can be achieved ...
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... MCH_PG DPRSLPVR STP_CPUB PSIB PGND FREQSET SENSE 10Ω 1nF 13 7 – VID0 SENSE 14 VID1 LTC3734 15 RBOOT 12.7k VID2 1% 13. VID3 RBOOT 56. VID4 RDPRSLP 1.27M 19 9 VID5 RDPSLP PGOOD 13. OAOUT ...
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... U UH Package 32-Lead Plastic QFN (5mm × 5mm) (Reference LTC DWG # 05-08-1693) 0.70 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 0.75 ± 0.05 0.00 – 0.05 3.45 ± 0.10 (4-SIDES) 0.200 REF LTC3734 BOTTOM VIEW—EXPOSED PAD 0.23 TYP R = 0.115 (4 SIDES) TYP 31 32 0.40 ± 0. (UH) QFN 0603 0.25 ± 0.05 0.50 BSC ...
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... LTC3734 RELATED PARTS PART NUMBER DESCRIPTION LTC1530 High Power Step-Down Synchronous DC/DC Controller in SO-8 LTC1628/LTC1628-PG/ 2-Phase, Dual Output Synchronous Step-Down LTC1628-SYNC DC/DC Controllers LTC1629/ 20A to 200A PolyPhase Synchronous Controllers LTC1629-PG TM LTC1702 No R 2-Phase Dual Synchronous Step-Down SENSE Controller LTC1703 No R 2-Phase Dual Synchronous Step-Down ...